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Commit 84f101c

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Pr0-C0dernightmare10123MaximSmolskiypre-commit-ci[bot]
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Add/generate parentheses iterative approach (#10024)
* Generate parantheses iterative * Generate parantheses iterative * Generating parantheses code using iterative approach * Update generate_parentheses_iterative.py * updating DIRECTORY.md * Update generate_parentheses_iterative.py * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Update generate_parentheses_iterative.py * Update generate_parentheses_iterative.py * Update generate_parentheses_iterative.py --------- Co-authored-by: nightmare10123 <pgadekar10123@gmail.com> Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru> Co-authored-by: MaximSmolskiy <MaximSmolskiy@users.noreply.github.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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‎DIRECTORY.md

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* [Combination Sum](backtracking/combination_sum.py)
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* [Crossword Puzzle Solver](backtracking/crossword_puzzle_solver.py)
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* [Generate Parentheses](backtracking/generate_parentheses.py)
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* [Generate Parentheses Iterative](backtracking/generate_parentheses_iterative.py)
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* [Hamiltonian Cycle](backtracking/hamiltonian_cycle.py)
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* [Knight Tour](backtracking/knight_tour.py)
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* [Match Word Pattern](backtracking/match_word_pattern.py)
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def generate_parentheses_iterative(length: int) -> list:
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"""
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Generate all valid combinations of parentheses (Iterative Approach).
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The algorithm works as follows:
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1. Initialize an empty list to store the combinations.
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2. Initialize a stack to keep track of partial combinations.
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3. Start with empty string and push it onstack along with the counts of '(' and ')'.
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4. While the stack is not empty:
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a. Pop a partial combination and its open and close counts from the stack.
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b. If the combination length is equal to 2*length, add it to the result.
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c. If open count < length, push new combination with added '(' on stack.
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d. If close count < open count, push new combination with added ')' on stack.
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5. Return the result containing all valid combinations.
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Args:
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length: The desired length of the parentheses combinations
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Returns:
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A list of strings representing valid combinations of parentheses
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Time Complexity:
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O(2^(2*length))
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Space Complexity:
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O(2^(2*length))
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>>> generate_parentheses_iterative(3)
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['()()()', '()(())', '(())()', '(()())', '((()))']
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>>> generate_parentheses_iterative(2)
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['()()', '(())']
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>>> generate_parentheses_iterative(1)
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['()']
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>>> generate_parentheses_iterative(0)
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['']
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"""
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result = []
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stack = []
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# Each element in stack is a tuple (current_combination, open_count, close_count)
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stack.append(("", 0, 0))
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while stack:
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current_combination, open_count, close_count = stack.pop()
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if len(current_combination) == 2 * length:
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result.append(current_combination)
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if open_count < length:
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stack.append((current_combination + "(", open_count + 1, close_count))
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if close_count < open_count:
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stack.append((current_combination + ")", open_count, close_count + 1))
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return result
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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print(generate_parentheses_iterative(3))

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